Python string startswith() and endswith() methods

The startswith() and endswith() methods are built-in Python string methods used to check whether a string starts or ends with the specified substring or sequence of substrings. Both methods return a boolean value: True if the string starts or ends with the specified substring(s) and False otherwise.

Here is a step-by-step tutorial on how to use the startswith() and endswith() methods in Python:

Syntax:
The startswith() and endswith() methods have the following syntax:
```
string.startswith(prefix, start, end)
string.endswith(suffix, start, end)
```
- prefix / suffix: The substring or a tuple of substrings to check if the string starts/ends with.
- start: (Optional) The starting index of the search. Defaults to 0.
- end: (Optional) The ending index of the search. Defaults to the length of the string.

Basic usage:

To check if a string starts or ends with a specific substring, call the startswith() or endswith() method with the desired substring as an argument:

text = "Hello, how are you?"

starts_with_hello = text.startswith("Hello")
ends_with_question = text.endswith("?")

print(starts_with_hello)  # Output: True
print(ends_with_question)  # Output: True

Using start and end parameters:

You can limit the search by specifying the start and end parameters:

text = "Hello, how are you?"

starts_with_how = text.startswith("how", 7, 10)
ends_with_are = text.endswith("are", 0, 14)

print(starts_with_how)  # Output: True
print(ends_with_are)  # Output: True

Checking multiple substrings:

You can use a tuple of substrings to check if a string starts or ends with any of the specified substrings:

text = "example.txt"

starts_with = text.startswith(("example", "sample"))
ends_with = text.endswith((".txt", ".md"))

print(starts_with)  # Output: True
print(ends_with)  # Output: True

In summary, the startswith() and endswith() methods are useful for checking whether a string starts or ends with a specific substring or sequence of substrings. They are commonly used in tasks like string validation, filtering, and pattern matching.

How to Use startswith() in Python for String Matching:
- Use startswith() to check if a string starts with a specified prefix.
```
# Example
text = "Python is powerful"
starts_with_python = text.startswith("Python")
```
Checking String Endings with endswith() in Python:
- Use endswith() to check if a string ends with a specified suffix.
```
# Example
file_name = "document.txt"
is_text_file = file_name.endswith(".txt")
```
Conditional Statements Using startswith() in Python:
- Employ startswith() in conditional statements for prefix-based checks.
```
# Example
text = "Hello, World!"
if text.startswith("Hello"):
    print("Greeting detected.")
```

String Prefix Matching with startswith() in Python:

Perform string prefix matching using startswith().

# Example
sentence = "Python programming is fun"
starts_with_python = sentence.startswith("Python")

Python endswith() for Checking Suffixes:
- Utilize endswith() to check if a string has a specified suffix.
```
# Example
file_name = "image.jpg"
is_image_file = file_name.endswith((".jpg", ".png"))
```
Matching Multiple Prefixes with startswith() in Python:
- Check if a string starts with any of the specified prefixes using startswith().
```
# Example
text = "Python is versatile"
starts_with_languages = text.startswith(("Python", "Java", "C++"))
```
Case-Insensitive Matching with startswith() and endswith() in Python:
- Perform case-insensitive matching using lower() or casefold().
```
# Example
text = "Python is case-insensitive"
starts_with_python = text.lower().startswith("python")
```
Handling Unicode Characters with startswith() and endswith() in Python:
- Use startswith() and endswith() with Unicode characters.
```
# Example
unicode_text = "𝒫ython 𝒾s ℂool"
starts_with_unicode = unicode_text.startswith("𝒫")
```
Efficient Ways to Use startswith() and endswith() in Python:
- Optimize performance by using startswith() and endswith() judiciously.
```
# Example
text = "Efficient programming"
is_efficient = text.startswith("Eff") and text.endswith("ing")
```